1) Field of the Invention
The present invention generally relates to a drive structure for a lawn and garden tractor that carries and powers an implement such as a rotary mower. More specifically, though not exclusively, the present invention relates to a pivoting idler assembly for a belt driven mower which is easily removable.
2) Related Art
There are many conventional mowing vehicles which use a belt and pulley system to transmit power from a vehicle power source, such as the vehicle""s crank shaft or transmission, to the blades of the mower. A drive assembly typically transfers power from the vehicle power source to a rotating drive pulley. The rotating drive pulley engages a drive belt which in turn powers a plurality of blade pulleys. The blade pulleys are connected to corresponding blade spindles to turn the mower blades. An idler pulley is typically installed to engage and tension the relatively slack or loose portion of the drive belt. Proper tensioning of the drive belt ensures the proper friction between the drive belt and the blade pulleys to prevent slippage. The belt tension applied by the idler pulley also generally prevents slack from accumulating in the belt, and thereby generally prevents the belt from becoming disengaged from the various pulleys during operation.
Conventional tensioning mechanisms provide a tension spring mounted to the idler arm for pulling the idler arm in a direction that will press the idler pulley against the belt and thereby tension the belt.
Occasionally, a large amount of tension can be placed upon the drive belt by other pulleys. This situation occurs when the mower blades strike an object and/or decelerates rapidly. The large amount of tension applied to the drive belt will pull or move the idler pulley and idler arm to such a degree that a condition known as belt whipping occurs. Belt whipping can cause the belt to disengage one or more of the pulleys. To limit the idler arm movement, many conventional mower decks include a bumper mechanism that abuts the idler arm. The bumper helps to prevent the belt from disengaging the pulleys after an obstruction has been struck or another situation applies a great amount of tension to the belt.
Current idler assemblies contact the bumper over the idler pulley. This makes removal of the idler pulley difficult and often requires that additional parts, such as the bumper, also be removed prior to replacement of the drive belt. It is therefore desirable to have an idler assembly in which the bumper is contacted beyond the radius of the idler pulley.
Further, most conventional idler assemblies are secured to the mower deck with a bolt which must be installed or removed from underneath the mower deck. This forces the user to access both the top and bottom of the mower deck. This increases the amount of labor necessary to remove or install the idler assembly. It is therefore desirable to have an idler assembly which is easily removable by simply accessing parts on top of the mower deck.
It is therefore an objective of the present invention to provide an idler assembly which overcomes most or all of the above-listed disadvantages.
It is another objective of the present invention to provide a pivoting idler assembly which is easily removable from a mowing deck for servicing or replacement.
It is a further objective of the present invention to provide an idler assembly which contacts a bumper or snubber beyond the radius of the idler pulley.
An idler assembly constructed in accordance with the teachings of the present invention includes a shouldered shaft mounted through a bracket to a mower deck by a bolt or other securing device. An idler arm includes a hole which corresponds to the width of the shouldered shaft. The idler arm is then placed over the shouldered shaft for pivotal rotation about the shouldered shaft. The idler arm is secured to the shouldered shaft by a spring clip or other easily removable securing mechanism. An idler pulley is rotatably secured to the opposite end of the idler arm. A spring retaining bracket is also secured to the idler arm. A spring connected to the spring retaining bracket provides the necessary tension force for the idler assembly.
The idler arm preferably includes an extension which protrudes beyond the radius of the idler pulley. The extension forms the point of contact of the idler arm with a bumper or snubber. The snubber is attached to the mowing deck by a snubber bracket. In this manner, neither the snubber nor the snubber bracket need extend over the idler pulley.